Investigation of the mechanical and microstructure of stainless and tempered steels joined by friction welded

Friction welding is a welding method used to join two different or same types of materials that are difficult or impossible to join by using friction time, friction pressure, rotational speed, forging pressure and forging time parameters. In the study, AISI 316L stainless steel and AISI 4340 tempered steel were combined by friction welding method using 3 different rotational speeds (2000, 2200, 2400 rpm) and 3 different friction time (3, 5, 7 sec) parameters. Mechanical tests and microstructural studies were carried out to determine the effects of welding parameters on the joints. In addition, the increase in flange diameters and shortening changes in length were also measured. In the results of study, when the macro and micro images of the welded samples were examined, no hollow structure was observed in the welded joints. The flange diameter and shortening variation occurred in the coupling with the highest speed and the highest friction time. The maximum flange diameter was 19.44 mm and the maximum shortening was 6.12 mm. Microhardness values; increased in parallel with friction time and rotational speed. Among all the samples, the highest microhardness value was measured as 771.9 HV and the lowest microhardness value was measured as 673 HV. The tensile test gave the best results in the sample where the friction time is minimum and the rotation speed is maximum. The maximum tensile force was 45726.56 N and the maximum elongation was measured as 14.532 mm. The maximum torsion torque was measured as 84.96 Nm and the maximum torsion angle was 1850.700, thus the optimum result was achieved within the torsion test results at the maximum friction time and minimum friction speed.